1. Field of the Invention
This invention relates to computers and, in particular, to information storage devices.
2. Description of the Related Art
Known in the art is an information storage device comprising a cylindrical information carrier with a recording layer applied thereon and a mirror disposed inside said carrier (JP, B, 53-2694).
Information can be recorded on this cylindrical information carrier and read therefrom by a laser beam using the mirror located inside the carrier.
The disadvantage of this prior art storage device consists in its low volume density of data recording, which can be explained by that, first, only one recording layer is used, second, this recording layer is left unprotected against environmental effects, and, third, the diameter of the cylindrical information carrier is relatively large since its positioning device is arranged inside said carrier.
Also known in the art is an information storage device wherein an optical information carrier comprises a hollow cylinder, a recording layer applied onto the external surface of this hollow cylinder, and a second cylinder external to the first cylinder and transparent to laser radiation. Two annular sealing elements are arranged between the cylinders so that a cylindrical closed space is formed between them and adjacent to the recording layer of the hollow cylinder (GB, B, 1580398).
The two cylinders are not permanently connected since the material of the recording layer requires development after information has been recorded thereon and, consequently, access to the material of this recording layer has to be provided by separating the two cylinders.
Another disadvantage of this prior art storage device is its low storage volume density since only one recording layer is used and this recording layer is not protected from the environment in any way and, consequently, can be covered by dirt, which affects the storage surface density of the recording layer.